Normally input devices are rotating pointing devices or sliding devices for controlling the pointer on the user interface. Examples of rotating pointing devices are a scroll wheel (also know as roller in apparatuses such as mobile phones), a rotator, a rotating knob, a trackball, etc. Basically the rotating or sliding pointing device is provided with one degree of freedom (1-DOF). Thus it can rotate in a plane. The scroll wheel will be presented here as an example because of its clarity. Thus the scroll wheel is basically a pointing device with one degree of freedom (1-DOF).
There are two types of scroll wheel, which may look similar, but function quite differently. The type of scroll wheel used e.g. on the Logitech Mouseman mouse, is an ideal input device for scrolling short lists. The wheel can rotate freely, but preferably a mechanism is incorporated for providing tactile clicks to select the lines or items in the list. The clicks enable accurate and very comfortable scrolling. The pointing method used here is called the position control method. The rotational position of the wheel corresponds one-to-one with the position of the pointer or highlight in the list. Note, that the ‘positions’ of the wheel can cover more than 360 degrees of rotation.
A problem arises if the movable distance is long, e.g. the list contains tens or hundreds of items, as is typically the case with lists of music in music players (or lines of text in a document etc.). Here, the pointer (or cursor or highlight, depending on application) needs to travel long distances. With position control method the user is forced to turn the wheel even many revolutions, which is slow and fatiguing.
Moving the pointer long lists is easier with the second type of scroll wheel. This type is spring-centered and can be deflected from the center-position maybe only about 45 degrees in either direction. The pointing method used with it is called the velocity control method. The pointer moves with a speed which is relative to the angle the scroll wheel is deflected from its center position. An example of a spring-centered scroll wheel is found on the Wacom mouse used with Wacom Intuos graphics tablets.
The haptic feedback provided by the spring is needed for controlling the pointer speed. Also, simply letting go of the scroll wheel can stop the pointer. Without spring centering it is very difficult to find the center position and stop the pointer.
With a spring-centered scroll wheel, using the velocity control method, you can move the pointer quickly. Unfortunately, the pointing action is not as accurate as with the position control method of a freely rotating scroll wheel. So, the problem with prior art solutions is that you can have either fast pointing or accurate pointing depending on the type of scroll wheel you have on your device.